An information as to the activity pattern and the amount or intensity of physical activity of pupils in physical education class is not only theoritical interest, but such information is essential for making up a teaching program of education. Untill now, however, no method for recording of physibal activity has been established, data have been obtained by retrospective questionaries, observation (time-study method) and measuring of heart rate over extensive periods. These methods are too cumbersome or expensive. The purpose of this study was to develop the new device for recording physical activity of pupils in physical education class as an actogram. A pedometer was used to detect the physical activity. A micro-switch was set to convert the pedometer signal to electric one, because it is advantageous for processing of data by computer. The pedometer count was memorized in IC memory of which capacity was 32-kbyte. The memorized pedometer count was fed into personal computer through an interface and after processing, it was displayed as the actogram representing the physical activity pattern of pupils in the class. The new device developed in this study could serve as a practical assessment tool for the physical activity pattern of pupils, because it is so small (110 mm × 70 mm × 30 mm) and light (170 g), no disturbance of physical activity, convenient to handle as well, and furtheremore less expensive.